Add glance api v2 testing.

This commit adds initial support for the glance v2 api. It adds
some basic image tests and a new v2 client. The client supports
create, get metadata, store, get image, and delete.

Change-Id: Ic8c79356d4dcadc35bb3a7aa0deac2336e370827
Merge "Add glance api v2 testing."